Pro-Ject Pre Box S2 Digital DAC/Preamplifier

Small Is Beautiful

Ergonomics and SetupConsidering how limited the Pre Box S2 front-panel space is (the entire surface is 1.4" by 4"), the area includes a remarkable number of controls and a good deal of display information. On the left side you’ll find the ¼" stereo headphone output. The center area is filled by a 7/8" by ¾" color display, which is flanked on the left by up/down input buttons and on the right by the filter and menu selection buttons. The right side of the Pre Box S2 holds the volume control knob. The rear panel of the Pre Box S2 has three inputs—USB, TosLink, and RCA coaxial SPDIF—along with one pair of single-ended RCA outputs and a Type C USB 5-volt power connection.

Setting up the Pre Box S2 was as simple as plugging in its wall-wart power supply, inserting a USB cable, connecting the unit to a power amplifier and subwoofer, and finally selecting the Pre Box S2 as my designated sound output device via my Mac’s midi control. Because the Pre Box S2 has only a single pair of variable analog outputs, I resorted to a splitter to supply a second output pair to drive my amp as well as my subwoofer.

Since the Pre Box S2 has its own dedicated, fully featured remote control, which can perform all control functions, you can place the Pre Box S2 almost anywhere within line of sight of the remote. Instead of putting it on my desktop I placed the Pre Box S2 under my desk, right on top of a power amplifier, connected to the amp via a six-inch length of Kimber KCAG cable.

Although the centrally located display is small, it transmits plenty of useful information. Not only does it display the current volume settings of the 80-step volume control, but it also tells you the current bit-rate, current input source, whether the signal is MQA, and finally, whether the Pre Box S2 is connected to an external power supply (as opposed to being powered by your computer’s USB connection).

I used a multiplicity of playback apps and audio sources via my Mac Pro desktop with no hiccups. I tried Pure Music, Amarra 4, Audirvana+, iTunes, the Tidal app, Internet Radio URLs via Safari and Firefox, YouTube videos, AudioTest frequency sweeps, and Roon. Even switching back and forth from MQA to non-MQA tracks via Tidal generated no drop-outs.

I connected a wide variety of headphones to the Pre Box S2. With the most sensitive in-ears, such as the 119dB Empire Ears Zeus, there was no detectable hiss, and at normal listening levels the Pre Box S2’s volume setting read -57dB. Going to the opposite extreme I connected the Beyer Dynamic DT-990 600-ohm version. To get the same volume levels the Pre Box S2 volume was turned up to -14dB. With the HiFIMan HE-1000 V2 the volume setting ended up at -18dB. Given that the vast majority of headphones and in-ears will fall somewhere between the 119dB-sensitive Zeus and the Beyer Dynamic DT-990s, I feel secure in saying that the Pre Box S2 will work successfully with most headphones.

I mentioned the Pre Box S2’s remote earlier. It’s “credit-card” sized but within its confines are all the adjustments you need to control the component. The layout shows some thought, with the mute button at the top center where even a first-time user will find it instantly. Volume up and down are also easy to locate, which is not always the case with many third-party, off-the shelf remotes.

The Project components were designed to be used together as the building blocks of an audio Erector set. By adding the Stream Box S2 Ultra to the Pre Box S2 you gain a streaming source, so you can use the Pre Box S2 without being tethered to a PC or a laptop. Add the CD Box S2 and you can play all your “legacy” CDs. Soon-to-be-available external power supplies—the Accu Box S2, Accu Box S2 USB, and Power Box S2—promise even lower-noise options for the expanding S2 eco-system, which as I indicated earlier, has miniaturized audio devices for almost every audiophile need.